Psoriasis is a common dermatosis affecting approximately 1-3% of the US population regardless of gender, age, ethnicity, or income group. Psoriasis is chronic, relapsing, and may be disabling. The presentation may be variable with some patients having only elbows and knees involved while others have 50% or more of their body surface area involved. Therapy depends on the severity of the disease. Treatment ranges from mild topical medications to potent parenteral drugs requiring hospitalization. Evidence implicates psoriasis as an immune disorder; mainly Th1. Activation of lymphocytes, as seen in psoriasis, results in interleukin-2 (IL-2) and interferon gamma (IFN-g) release. IFN-g interacts with many cell types and stimulates cytokine release. Ultraviolet light, in the 'B' spectrum, (UVB, 290-320nm) has been used for many years to treat psoriasis and is very effective, Evidence has demonstrated that UVB light is immunosuppressive and that a narrow portion of the UVB spectrum, 312nm or NB-UVB, is particularly effective. Data from our laboratory indicates that NB-UVB light reduces the abnormally high levels of IFN-g expression in psoriatic skin as well as other genes regulated by IFN-g. For example, expression of IL-8 and IL-12 are reduced by NB-UVB. Our gene array data shows that the STAT1 gene, regulated by IFN-g, is modulated by NB-UVB. Our plan is to treat psoriasis patients with NB-UVB light, and then assess the cytokine and immune cell trafficking patterns in both skin and peripheral blood using RT-PCR, gene arrays, and immunohistochemistry. Current efforts towards new anti-psoriasis therapies focus on immunobiologics. For the near future, rotational-combination of new and old therapies will be the mainstay in treating psoriasis. Successful implementation of rotational-combination therapies depends on understanding molecular mechanisms of action. These studies will help us design rational rotational-combination therapies. In the future, individualized therapy, based on each patient's genetics, is the goal.